


Just Desserts

by SesuRescue (Kigachan)



Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap, Anal Fingering, Anal Sex, Ecto-Penis (Undertale), Ecto-Tongue (Undertale), Explicit Language, Explicit Sexual Content, Multi, Sexual Coercion, Underswap Papyrus, Underswap Sans, Underswap!Grillby referenced as Swirlby, anal licking, established Swapcest, underswap Grillby
Language: English
Status: Completed
Published: 2017-09-15
Updated: 2017-09-15
Packaged: 2018-12-30 03:39:37
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 6,356
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12099897
Author URL: https://archiveofourown.org/users/Kigachan/pseuds/SesuRescue
Summary: Blue brings Stretch to a hangout session with his new friend





	Just Desserts

**Author's Note:**

> I'm not good with this whole PWP thing...maybe more like P(With)P haha.

If there was one thing Stretch loved than anything in the world, it was his brother, Blue. He loved that Blue was sweet, compassionate, and the most driven monster he'd ever met. Blue managed to work hard enough to make anything happen, even convincing Stretch to date him in a not-so-brotherly way. Maybe that's why when Blue brought up taking him to meet his new friend that day, Stretch knew there was no use in arguing. 

The talk had happened earlier that morning while the two of them were cuddling after a particularly enjoyable romp. Blue, holding a reclining Stretch to his chest, asked him if he had any plans that day or things he wanted to do. Stretch thought on it, previously considering either bothering Muffet or talking to the man behind the door, but he couldn't turn down his brother. 

_ “i don't think so, why what's up?”  _ he had asked casually. He peered back at him to see Blue grinning, starry eyes twinkling as he held Stretch’s waist. 

_ “I made a new friend, and they invited us over for snacks!” _

So now, Stretch was following Blue to their destination, hands in his pockets as he listened to his brother chatter about the monster they were going to see. 

“I met them one day while I was with Alphys,” Blue said happily as they boarded a boat, taking a seat. “I accidentally knocked something of theirs over, and while I was helping them get organized we started chatting!”

“yeah?” Stretch took a seat beside Blue, lacing their hands together as he slouched against the backrest. Blue frowned slightly. 

“Papy, don't slouch! Anyway, yeah! We talked about the normal stuff, you know; the weather, what we do in the Underground, and over the next couple of days we kept running into each other, so I figured we should have a friend hang out session!”   
  


“no offense bro, but if they’re your friend, why am i coming?” Stretch asked.

“Because Papy, I want my friends to be your friends! Also…” Blue simmered down, gazing away as he clutched at his scarf. “I’m a little nervous, so having you there to support me will be helpful.”

Stretch turned to face Blue, brushing his hand down the side of Blue’s skull. “hey, you’re gonna do great, bro. that monster is going to have no choice but to be your new super cool friend, and i want to meet them so i can properly give my seal of approval.” He placed a chaste kiss against Blue’s teeth, making them both giggle. “so, where does this guy live?”

“Oh, he lives in Hotland!”

The boat slowed as it approached the pier, coming to a rest as the River Person showed the two skeletons off, giving them a wave as the boat drifted to its next destination. Blue led the way, leaving Stretch to bask in his thoughts as they walked. It had been a long while since he was last in Hotland. He used to come here more frequently to laze around and sell shitty hotdogs, but since  _ the incident _ he hadn’t really been back except to pass through, and even then he kept his senses sharp, listening out for the crackling of fire or soft laughter. 

As they ventured further into Hotland, Stretch stripped off his hoodie, wrapping it around his waist to keep himself cool. They passed by Undyne’s lab, Stretch giving a small wave into the camera to let his friend know he was thinking of her. He hadn’t visited her in awhile; maybe he should swing back to say hi after he and Blue finished their visit. Stretch wasn’t sure if Blue had met her yet, but he knew that they could become fast friends easily if they tried. 

“hey bro, ever meet undyne before?” Stretch asked, shuffling behind.

Blue regarded him over his shoulder as he slowed, scratching his head. “Maybe? I think we’re UnderNet friends.”

“if you want, after we finish meeting your friend, we could visit undyne. we’re friends, so i’m sure she wouldn’t mind if we popped by.”

“Hmmm…maybe!” Blue replied absently, speeding up. Stretch shrugged, jogging slightly to keep pace with his brother.

After a while, Blue stopped suddenly, causing Stretch to almost run into him. “Papy, we’re here!”’

Stretch eyed the landscape, at first seeing nothing but the rocks of Hotland, until his eye caught the bright purple hue of a fancy door on the wall in front of them. A door, in the middle of Hotland? Who could stand to live here? A strange feeling crawled up his neck as he bent over to whisper in Blue’s ear. “who did you say your friend was again?”

Before Blue could answer, the door opened, revealing a flame elemental wearing a brightly colored tuxedo. “Hello dearies~”

Stretch stiffened, thoughts short-circuiting as he came face to face with him again. Swirlby. The reason he avoided Hotland like the plague. The  _ incident _ himself, in the flesh.  _ Still looking as hot as ever, holy shit.  _

He remembered his first, and only(until now), encounter with Swirlby. He had been walking through Hotland, ready to slack off at Muffet’s cafe, when he noticed a small, unassuming stand ran by a cheerful fire elemental, Swirlby. 

Swirlby had offered him a sample of his homemade rock candy, and Stretch couldn’t resist the sweet call of free samples, but little did he know that they actually had a steep price. Swirlby demanded an exorbitant amount for the candy, and when Stretch couldn’t pay up he suggested an alternative method of paying; a good dicking. Stretch was pretty enamoured with the lithe elemental, and confident enough in his lovemaking skills to do a good job, but Swirlby managed to overpower him and fuck him until he passed out, exhausted. Stretch didn’t he’d ever be quite the same after that.

Now here he was again, and friends with his brother?

“s-so, this is your friend, huh?” Stretch ground out, trying his best not to panic.

“Yep! This is my new friend, Swirlby. Swirlby, this is Papyrus!” Blue grinned, gesturing at Stretch expectantly. 

Stretch stuck his hand out, grasping Swirlby’s hand to shake it. “nice to meet you…” He quickly surveyed Swirlby’s face, the glint he caught in his eye making Stretch’s knees shake. Fuck, he remembered.

“A pleasure to meet you~” Swirlby purred, clasping Stretch’s hand with both of his own. “Blue has told me a lot about you~”

Stretch let out a shaky chuckle. “he has, huh? he told me almost nothing about you, heh.”

Swirlby laughed airily. “We just met recently~ He helped me collect some of my things one day, and now all we do is chat the day away. Blue is such a charming monster, so I couldn’t turn down an invitation to hang out~ Would you two like to come inside?”

Blue followed Swirlby through the door, leaving Stretch out in the doorway. He considered running away; by the time the two of them noticed he wasn’t there he could be halfway to Snowdin already.

Blue’s voice echoed from inside. “Papy?? Where are you?” 

Heaving a sigh, Stretch cursed every deity he knew of as he walked inside.

~~~~~~~~~~~~~~

The interior of Swirlby’s house was not at all what he was expecting, but then again, he wasn’t sure what he thought it would look like. Hell, maybe? The space was split up into large room-sized caverns, separated by natural rock walls. He stood in what he assumed to be the living room, based on the decour. There was a small cream colored couch, littered with large pastel-colored throw pillows, and an end table piled high with various rocks. Fire ants skittered on the walls, scrutinizing Stretch as he walked through the living room to the next room over.

“Oh, there you are!” Blue exclaimed.

Blue was sitting at a rectangular table, adorned with a kettle of tea and a multitude of sweets. There were cakes, crumpets, cookies, and candies meticulously arranged on the table to appear as neat as possible. Swirlby stood beside Blue, widening his arms in welcome. 

“Ta-da~! A tea party for us~ Please, sit, and get comfortable~” 

Stretch took a seat at the chair nearest him, across from Blue and Swirlby at the table as his eyes pored over the spread. Wow, everything smelled amazing; he couldn’t believe that Swirlby had made all of this. It's like the fire elemental thought of every sweet thing that existed and baked it, just for them. 

Now that Stretch thought about it, this whole setup did kind of seem like the type of thing that suited Swirlby perfectly, based on what little he knew of him. Cute furniture, a table of sweets, and he probably had a pristine kitchen too. When he was with Swirlby, he was taken to a large cavern with a huge lava pool. He idly wondered where that place fit into Swirlby’s housing layout, or if it was even attached to his house. Did Swirlby bring him home to fuck, or did he take him somewhere else? Why was he thinking so hard about this? Didn’t he want nothing to do with this guy?

Stretch observed Blue, who was laughing at something Swirlby said. He loved the way Blue’s face lit up when he was happy. It was like the stars themselves shined on him, making him the brightest part of his life. He rested his skull on his palm, watching them converse until he realized… Blue wasn’t a fan of sweets, right? 

“hey blue,” Stretch called, getting his brother's attention. “are you okay with all this? i mean, you don't really like-”

“Honey?! You're right, brother, I guess you can have it! I love everything else though, especially after Swirlby went through  _ such _ great efforts to put out this spread  _ just for us.”  _ Blue interrupted, voice taking on a rare low tone as a warning to not mess this up for him. 

Stretch raised his hands in surrender as he slouched back in his chair. He forgot how gung-ho the smaller skeleton got when he was trying to make a good impression. He was pretty sure that Blue would probably jump off the roof if it meant he could make a new friend. If Blue wanted to have a sugar crash later, that was his own business. 

Stretch searched the table, searching for his first prey, when his eyes landed on a small crumpet. Perfect. He pulled the crumpet towards him and slathered it in honey, mouth drooling at the delicious sight. Picking up a fork and knife, he dug into the pastry, reeling from the flavor. It was just the right amount of sweet and savory to make his nonexistent taste buds soar. 

“Oh my, these cherries are so tasty~ ” Swirlby gushed from the other side of the table, interrupting Stretch’s precious moment. 

Stretch glanced up to reply, nearly choking from the sight before him. Swirlby was staring dead at him, smirk on his face, as he stuck his tongue out to slowly lap at a cherry he was holding. Stretch remembered that tongue, and how it slid so deliciously over his cock before... _ wait, no, bad Stretch! You can’t be having these thoughts while your boyfriend is around! _

Darting his eyes quickly, Stretch glanced at Blue, hoping that he wasn’t witnessing the brazen display. To his relief, his brother was turned the other way, trying to decide which dessert to eat. He met Swirlby’s eyes again, mesmerized by that orange flame tongue of his curling around the small fruit. Swirlby brought the cherry to his mouth, sucking on it lightly before popping it into his mouth with a groan. 

_ fuck,  _ Stretch thought as his cock manifested itself, hard and weeping from Swirlby’s teasing. He gazed out of the corner of his eyelights at Blue again, surprised that he didn't hear the noises spilling from the flame elemental’s mouth. Was he actually that oblivious?

Stretch focused again on Swirlby, noting that he clutched yet another cherry in his hand, apparently waiting for Stretch’s full attention before continuing. This time he focused more on sucking, bobbing the cherry in and out of his mouth while flicking his tongue over it. Mouth gaping open, Stretch couldn't help but whimper slightly at the slurping sounds Swirlby was making, which were deceptively close to a far more vulgar act.

Shifting slightly to adjust his suddenly constricting shorts, Stretch tried to ignore Swirlby’s actions as he took a huge spoonful of honey into his mouth to distract himself. Mmm, honey...sweet, delicious honey, truly the nectar of the gods. He could eat this stuff forever, just gulp it down while he watched Swirlby gulp down something else from him….wait, what? Before Stretch could reflect on his thoughts, a shrill beeping sound came from somewhere behind him.

“Oh~ the pie!” Swirlby exclaimed, standing up and dashing towards the kitchen. As he passed by Stretch, he dropped something into his lap. Curious, Stretch searched his pants, phalanges catching onto something small. Was this it? He bent his head down towards his hands to get a better glimpse. It was… a cherry stem, tied in a perfect knot. Stretch flushed, orange covering his face as he realized the implications of this and the show from earlier. Swirlby was hardcore flirting with him. Didn’t Blue tell him that they were going out?

“Papyrus? Are you okay?” 

Stretch took a breath to calm himself down, giving Blue a lazy grin. “yeah, bro, i’m fine. are you having fun?”

“Yes! Swirlby is such a friendly monster and his sweets are to die for!” Blue exclaimed, moaning over a mouthful of cake. “I know I don’t usually eat sweet things, but these are just so good!” 

Stretch’s cock twitched, roused by the pleasure in Blue’s voice as he tried to calm down. Blue was just really enjoying his cake, nothing wrong with that. Removing one of his gloves, Blue dragged a phalanx across the icing on top, its deep orange color reminding Stretch of his own cum, something that Blue dabbled with frequently.

Before he could comment on it, Blue licked up the side of his finger, blue tongue contrasting nicely against the orange icing. Stretch concentrated with bated breath as his brother lewdly bathed his digit with his tongue, letting out small groans every now and again. He caught sight of the pearly white bone underneath, making him tremble with need. Their eyes met as Blue took his finger into his mouth whole. 

“blue, what are you doing?” Stretch hissed. He tried his best to sound angry, but he knew that the lustful undertones gave him away instantly. “swirlby’s gonna be back here any second!”

Blue ignored him as he finished sucking on his finger, sockets half lidded as he eyed Stretch. He replaced his glove and slowly left his chair, circling the table with an exaggerated sway of his hips. Swinging a leg over Stretch’s lap and balancing on the balls of his feet, Blue took a seat facing him, placing Stretch’s hand on the back of his neck. 

“You know what I'm doing brother,” Blue murmured, bucking his hips into Stretch’s with a moan. “Ahh P-papy, you feel so big and hard against me.”

Cursing, Stretch tightened his hold on Blue, rutting against him as he started to lose control of himself. “blue, oh my god. let's go home, right now. i can't hold back any longer.”

Blue giggled as he took Stretch’s thumb into his mouth. “Mmm, not yet, Papy,” Blue said around the intrusion. “After we're done here, we can go home. Then you can fuck me until I scream, okay?” Stretch nodded frantically, desperate for relief and grounding his aching length against the seat of Blue’s pants, noting that Blue was half hard. He closed his eyes as the pleasure built up, causing him to toss his head back in ecstasy. 

“I love watching you lose control, Papy. You get so aggressive, especially when you're pounding away at my ass,” Blue moaned, rubbing his magic through his clothes. 

The sound of footsteps interrupted Stretch from replying, opening his eyes in panic. Blue darted back to his seat just in time for Swirlby to come through the door, holding a large pie. There was a decent amount of whipped cream styled on top of the pie, making it appear taller than it probably was. “Sorry for taking so long~ the topping decided it wanted to be extra difficult today~”

Stretch slouched lower in his chair as Swirlby passed by him, trying to hide the obvious shining of his boner. He knew that his face was probably completely flushed, but he was past the point of caring. He just had to take a few quick bites of his dessert, say it was delicious, then teleport him and Blue home, easy enough. Swirlby hummed lightly as he cut three generous servings, sitting them out in front of each of them. “Bon appetit~”

Stretch picked up his fork, stabbing it into the pie and stuffing into his mouth. This pie was actually really good. He couldn’t quite discern the flavor though, was it cherry? Raspberry? Well, it didn’t matter as long as he ate enough to be polite. He really needed to get home. Stretch looked up, checking on Blue’s progress. Blue seemed like he was really enjoying it, Stretch reasoned, based on the large amount of whipped cream that ended up covering his jaw. “Hey bro, you got some on your face.”

Swirlby turned to Blue, astonished. “Oh dearie, you’ve made a mess! Here, let me clean you up~” 

Stretch figured that maybe Swirlby had a napkin close by to wipe off the whipped cream, maybe even a cleaning cloth. What he didn't expect was for Swirlby to lean in, mouth dangerously close to Blue’s, and lick the whipped cream right off of his face. Stretch’s thoughts crashed as he watched the flame elemental of his current daydreams drag his tongue over his boyfriend’s mandible, and for some reason, he wanted them to continue. He wanted to see Blue turn his head  _ just _ right to capture Swirlby’s mouth in a gentle kiss. 

Luckily, or unluckily, for him, that’s exactly what happened. Blue turned his head into Swirlby and pulled him forward to smash their mouths together. Swirlby’s mouth hung open in surprise, just wide enough for Blue to tangle his tongue with the other’s insistently. Both of them moaned into the kiss, pressing closer to each other as they made out. 

Stretch sat, dumbfounded as the events unfolded in front of him.  _ What the fuck, what the actual fuck???  _ He would pinch himself if he had skin, knowing that this must’ve been some crazy fever dream he was having. However, as he caught small flashes of orange and blue tongues from where his brother and Swirlby were connected, he knew that this was real life, and it was  _ hot as hell. _

Entranced, Stretch focused on the two monsters as they embraced, exploring the other’s body with their hands. Swirlby  wandered up to the soft ecto-flesh covering Blue’s cervical vertebrae, fingering his baby blue scarf, as Blue’s hands lingered down on Swirlby’s ass, cupping the cheeks. Stretch edged forward for a closer look as he brought his hand closer to his throbbing erection, unintentionally pulling the tablecloth closer to himself. With a loud clatter, the table tipped over, spilling hot tea and pie all over Stretch’s shorts.

“shit!” Stretch swore, standing and catching the attention of the other two monsters. Blue broke apart from the kiss first, rushing over to Stretch’s side.

“Papy! Are you okay?” Blue asked, checking over his brother to make sure he was okay. “Ahhh you’re all soaked!”

“it’s okay bro, it’s just a little bit of tea. let’s just head home and I can change-wait, what are you doing?” Stretch screeched as Blue started to unbutton his shorts.

“What does it look like? I’m cleaning you up!” Before Stretch could retort, Blue yanked his pants down, exposing him to the world. He immediately moved his hands to cover his shame, face burning bright. Blue sighed, pushing Stretch down into his chair and placing himself between Stretch’s femurs.

“Now now, Papy, none of that. I can’t clean you up if you’re being difficult.” Blue scolded lightly as held Stretch’s hands within his own, revealing his boner. His eyelights burst into hearts as he dipped in closer to the length, the magic radiating from Blue’s tongue making it twitch. “Ahhh, look at you, so hard and ready for me. Do you mind if I get a taste?”

Stretch distantly remembered that they had an audience, but he couldn't be assed to properly consider those facts when his brother was  _ right  _ in front of his weeping cock _ ,  _ ready to take the edge off, and he was  _ so horny _ . He nodded, too far gone to trust himself to speak normally. “go ahead, bro.”

Blue removed his hands from Stretch’s, using them for leverage on Stretch’s thighs as he dragged his tongue up the side of his cock, similar to the way he licked his finger earlier. Groaning, Stretch ran his phalanges over Blue’s skull, finally getting some relief after being teased for so long. As Stretch got lost in his brother's talented tongue, he didn't even notice a certain flame monster sneakily making his way over, until a foreign hand rubbed his knee.  “Hello darling~ Room for two?”

Stretch’s soul skipped a beat as he tried to jerk back. Blue noticed the motion, chuckling slightly as he mushed his nasal bone against Stretch’s dick in a cute gesture. “Papy, is it okay if Swirlby gets a taste as well? You taste so sweet that I just can't keep you all to myself.”

“ahh, uhm, okay,” Stretch answered. Blue moved to the side, holding Stretch’s hand against his skull as Swirlby took his place. He wasted no time in grasping the dick with his hand, peppering it with warm flame kisses. This was nothing like the feeling of cool ecto that Stretch was used to but…it wasn't unpleasant. Without any warning, Swirlby took him into his throat, sinking down until Stretch’s cock hit the back of his throat. Stretch moaned low as Swirlby gurgled happily. 

Swirlby was, as Blue was say, simply magnificent. His throat was warm and wet, and it constricted against his dick so tightly. It was almost as if Swirlby was made for sucking dick, and he seemed to know it as he handled Stretch expertly, finding every sensitive spot and attacking it with his tongue. Stretch shouldn’t have been enjoying this as much as he was but...it just felt so goddamn good. He took his free hand and patted Swirlby’s head, absently noticing that the flames were slightly malleable.  Before long, Stretch could feel the pressure building below, threatening to explode. “a-ah, i’m getting close...”

Swirlby looked up, meeting Stretch’s eyes and giving the cock one more good suck before pulling off. “Mmm, your cock is just as fantastic as I remember~ I would love to sit here and suck on it all night, but I think maybe we should relocate to my bedroom?” 

Blue lit up, vibrating slightly beside Stretch with happiness. “Yes, please!”

Swirlby shuffled onto his feet, winking suggestively in their direction before sashaying away towards what Stretch assumed was the hallway. Blue, quickly scrambled to his feet, intent on following, but Stretch seized him by the bandana and pulled him back. 

“just gonna chat with my bro first,” Stretch voiced, waving to Swirlby. Once he was around the corner, Stretch turned Blue around to face him, furious. “blue, what the hell are you doing?” He hissed. Blue sighed, rubbing his temples.

“Papy, do you remember what you said to me two weeks ago while we were fucking?”

“which time?” Stretch asked.

“Doggy style. You mentioned wanting to try a threesome, remember?”

Stretch did, now that he thought about it. He had been taking Blue from behind, and as he saw Blue pant into the air, he thought that his brother would look just perfect if he were sucking another monster’s dick. He mentioned it to Blue in the heat of the moment as dirty talk, but he didn’t expect him to actually try and follow up on it. It was pretty hot to fantasize about, and if given the option he would love to participate in one with Blue but, he would’ve rather talked it through first!

“i didn’t think you’d actually try and find someone without discussing it fully. also, why swirlby?”

“Swirlby recognized me as your brother, and asked about you. He told me how he knew you, and I figured if we were going to do this, it should be with someone you’re familiar with. Plus...I find Swirlby really attractive.” Blue blushed as he rubbed the back of his neck, clearing his throat before continuing. “So anyway, Swirlby and I came up with this idea to tease you and see how you felt about him, and I can tell you’re still very attracted to him.”

He wished that he could refute Blue's statement, tell him that he came to the wrong conclusion, but Stretch knew he’d be a liar. Swirlby’s actions hit him harder than he thought it would, and the attention that the fire monster was giving him made his soul yearn for more. It definitely didn't help that they had had sex before; knowing exactly what the fire elemental was hiding under his clothing made Stretch a little hot under the collar. 

“you make a good point. what do we do now, bro?” 

Blue shrunk slightly under his gaze, unconsciously gripping the bottom of his scarf. “Well, if you're up to it, AND FEEL FREE TO SAY NO, I thought maybe we could try it? It'll be super casual, don't worry, I already made sure Swirlby was okay with it.” 

It would be so easy to say no. Blue wouldn't mind, and they would go home, but…god, did he love making him happy.

“ok blue, let's try it.” 

Blue brightened, a thousand watt smile on his face as he engulfed Stretch in a tight hug. “Oh thank you, Papy! I promise you won't regret it, I love you!”

“i love you too, blue, so much.”

Holding hands, the two of them left the kitchen the same way Swirlby had earlier, coming face to face with a small stairwell leading up to a second floor. They walked side by side up the rock staircase, using their outside hands to balance as they traveled upward. Reaching the top, Stretch spotted a small lit doorway at the end of the walkway to their left, most likely the place where their friend went. 

Blue tried not to sprint to the doorway, walking briskly towards it with Stretch lagging slightly behind him. “We’re here! Are you ready…” Blue tapered off as he peeped in, skull flushing the same color as his namesake. Stretch peeked in over Blue, nearly fainting at the sight.  _ Oh my god.  _

Swirlby laid seductively on the bed, showing off his toned body. In between leaving the kitchen and now, he had stripped off his tuxedo and was clad in only his undergarments. Choosing a bright blue color theme, Swirlby had picked out a garter belt and thigh highs, frilly underwear, nipple pasties, and his bowtie to complete the ensemble. Laughing warmly, Swirlby stood up and walked over to the brothers, trailing a hand down each of their ribcages. “I've never had brothers before, how exciting~” He turned to consider Stretch. “I also haven't had a chance to kiss you today~ can I?” 

Stretch glanced at Blue, who gave him an enthusiastic thumbs up, before nodding. Swirlby moved in close to him, breath ghosting over his teeth, before closing the gap and mashing their mouths together. Groaning, Stretch pressed his tongue against Swirlby’s mouth, requesting access. When he parted his mouth, Stretch wasted no time in exploring it, wrapping his arms around Swirlby to rest against his back. 

The kiss broke slightly too soon for Stretch’s tastes, but he quickly latched onto Swirlby’s neck to compensate, humming in appreciation. Running his hands over Swirlby’s body, Stretch was surprised to find some of the sexy underwear he had on wasn't quite normal, and even the fire elemental’s signature bow tie was different than usual. It wasn't made of fabric, but something far more smoother and… slightly sticky? 

“mmm, what's this?” Stretch murmured, running his fingers curiously over one of the flat nipple pasties. “are these made of...candy?”

Swirlby bucked into Stretch from the stimulation, squeezing closer. “Ahhh yes~ Only the finest for you boys, but you’ll have to wait before you can partake~”

“guess i’ll just have to explore elsewhere for now.” Stretch grasped a handful of Swirlby’s ass and bit down gently on the other's shoulder, alternating between licking and biting as he grinded his clothed erection against the fire elemental’s body. Swirlby fisted his hands into Stretch’s tank top, moaning. 

The two monsters paused in their actions as they heard a low growl, turning around to see Blue sitting on the bed, hand in his pants and stroking his cock as he watched the two of them. He had taken his shirt off while the two explored one another, and the top of his ecto-body was on full display for them now. Stretch drooled over the thick muscle covering his bones, something Blue developed during all of that training with Alphys. It was especially attractive when Blue would demonstrate his strength by effortlessly changing their positions during sex. From the way Swirlby was staring, Stretch figured he might’ve been a bit smitten too. 

Taking advantage of Stretch’s momentary distraction, Swirlby kissed him again, spinning their positions and pushing him towards the bed as they clashed tongues. Before Stretch knew it, the kiss broke and he was falling, landing with a small  _ omph _ into Blue’s lap. Blue maneuvered Stretch so that he was sitting on the edge of the bed and crawled in between his legs to paw as his shorts. 

“Papy, I’m going to take off your shorts okay?”

Stretch nodded, lifting up his lower half to make it easier on Blue, checking out Swirlby as he kneeled down beside Blue on the floor. He gasped slightly when Blue pulled off his shorts in one shot, the cool air hitting him all at once. Blue and Swirlby exchanged eye contact, and Stretch could’ve sworn he saw the twinkle in their eyes before they both leaned forward to attack his dick with their tongues.

Stretch thought that both Blue and Swirlby were excellent separately, but he couldn’t even begin to imagine how dangerous the two monsters would be when they worked together. Blue and Swirlby switched off between sucking and licking in near perfect unison, changing it up right when Stretch thought he couldn’t take it anymore. If that wasn’t bad enough, the two began to sloppily make out above his dick, heightening his arousal. 

“holy shit, you two are amazing,” Stretch groaned out, resting his hands on their heads and resisting the urge to push their heads closer together.

Kissing once more, they parted and Swirlby climbed up into Stretch’s lap, taking off his tank top. “I’m glad we’re able to please you so well, but now it’s your turn~” Swirlby purred, pushing the skeleton back against the bed. Swirlby hovered over Stretch, glasses slightly askew as he gazed at Stretch’s naked body. Unlike Blue, Stretch’s ecto body was thinner and devoid of any muscle because of his sedentary lifestyle. He suddenly wondered if Swirlby wouldn’t be as attracted to him because of it, but to his surprise Swirlby bent down to caress his stomach in reassurance. “You’re perfect, dearie~”

“I tell him that all the time but he never believes me!” Blue piped up some somewhere behind Swirlby. 

Stretch blushed, deciding to occupy himself with exploring Swirlby’s chest using his tongue. He started at his nipples, gently prying the nipple pasties off and popping them into his mouth. Licking his teeth, Stretch ventured to the fire elemental’s neck, which was quickly becoming a favorite spot of his, and ran his tongue over Swirlby’s neck where his bowtie sat. He ran his hands over the other’s legs, dick twitching with interest as he smoothed over the silky material of the thigh highs. 

Swirlby adjusted his legs slightly as he burrowed his head into the bed beside Stretch to moan, nearly smothering him in his neck. Freeing himself slightly, Stretch used his newfound vantage to check out what Blue was doing. To his surprise, Blue was inserting a finger into Swirlby’s ass, eyes heart shaped as he panted around the candy thong he held between his fangs. Figuring that Swirlby could use a distraction, Stretch snagged him, kissed him wetly and holding onto his shoulders to keep him steady as Blue prepped him. After working at it for a while, Blue managed to get three fingers into Swirlby, accidentally brushing his prostate and making him scream. 

“Please stop teasing and fuck me already~!”

Stretch felt rather than saw Blue remove his fingers with a wet squelching sound as Swirlby’s body tried to follow them. He watched in amazement as his brother picked up and positioned Swirlby above his dick with little effort, muscles barely straining from holding up the fire elemental. 

“Are you ready for Papy’s cock?” Blue breathed into the side of Swirlby’s head, just loud enough for Stretch to catch in the silence. Biting his lip and shifting his eyes between Stretch and his dick, Swirlby nodded enthusiastically. Stretch held his cock steady as Blue lowered Swirlby down, gasping as he made contact with the puckered entrance. Swirlby rested his hands against Stretch’s ribcage as he ground his hips down, slipping the dick in to the hilt in one shot. 

“AHhhh~ I’ve missed this dick,” Swirlby said, wiggling his rump experimentally. “It’s a very good dick, one of my favorites~”

Stretch closed his eyes, digging his fingertips into Swirlby’s sides and trying to not immediately release inside him. His ass was even better than his mouth, if that was even possible. It was warmer than anything he had felt before, and tight enough to make him wonder if his dick might just fall off. Couple that with the excitement of the threesome, and Stretch was just barely hanging on. 

Cool bones gently caressed his mandible, making him open his eyes to see the smiling face of his brother hovering over him. “So, Papy, how does he feel?”

“oh my god blue, he feels amazing. it feels like my dick is going to melt. i wish you could experience this too.”

Blue chuckled as he clacked his teeth to Stretch’s forehead. “Don't worry, dear brother, I have to take my place at my throne.”

Stretch trembled as he realized what Blue meant, face breaking into a large grin. He heard the shuffle of clothing behind him as Blue undressed, rubbing Swirlby’s side as he waited. His cock twitched violently, making Swirlby quiver with the motion. 

A pat on the head was the only warning Stretch got before Blue straddled his face, plump cheeks smothering his face. He spread Blue’s ass wide, running his tongue over his asshole as he groaned in appreciation. Stretch loved giving his brother the best pleasure he could, and licking his ass might've been one of his favorite activities to unleash on him. Blue always loved it, based on the sounds he made, and right now it was no different. He cried out, bouncing slightly on Stretch’s face to bury his tongue farther into his hole. 

Wet, smacking sounds reached his ear holes as the two made out above him. Swirlby began to gyrate, arousing Stretch to no end after sitting inactive for so long. As the three of them continued to move together, Blue took Stretch’s hand, wrapping it around Swirlby’s dick to jerk him off. Stretch rutted hard into Swirlby as he tightened his grip, groaning as he felt himself getting close. 

“I-I'm coming~!” Swirlby shouted as his ass tightened hard around Stretch’s shaft. A warm liquid splashed against his ribs and spine, tipping him over the edge. Stretch thrusted up as he came in Swirlby, moaning into the space where he and Blue were connected. As the post-orgasm haze washed over him he distantly felt his tongue being constricted by his brother and a small scream as cum washed over him again. 

Stretch groaned softly as Swirlby and Blue slowly removed themselves, collapsing on either side of him to catch their breath. He wrapped his arms around each of them, looking down at his body to survey the damage. His ribs were covered with hardened molten cum and thick blue ectoplasm, mixing with his own cum that spilled from Swirlby’s ass. Lucky for him he knew that a quick warm bath would do the trick to removing all the cum no matter how long he waited.

“So Papy, what did you think?” Blue asked, propping himself up in his elbow. Swirlby sat up too, flames twitching nervously. 

“definitely something i’d like to try again,” Stretch said, after taking a moment to think. “preferably after a few actual dates so we can get to know the real you,” he added, pecking Swirlby where his nose would be. Swirlby grinned as he flopped back onto Stretch’s chest, blushing furiously, to Stretch’s surprise. Blue followed him, curling into Stretch’s side with a content sigh. 

Stretch wasn’t sure exactly what to make of Swirlby. He was a little eccentric, with an odd way to get what he wanted. But as he held the blushing monster in his arm, he knew that he had been smitten a long time ago, and he was really excited to get to know the other monster better, and maybe even initiate a relationship with him and Blue. Making a mental note to check which days he and Blue had off to schedule a date, Stretch drifted to sleep, holding both monsters in his arms.

  
  


**Author's Note:**

> Thanks for reading! <3 feel free to bother me at my NSFW tumblr: [Sesurescue](http://Sesurescue.tumblr.com)


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